The shortages and mounting costs of extracting fossil fuels such as oil, coal, and natural gas has caused a search for alternate sources of energy. At one time it was thought that fissile fuels which power nuclear reactors would bridge the gap when the cheap sources of fossil fuels became depleted. However, the long term availability of fissile fuels is questionable, safe breeder reactors are yet to be developed, and there is mounting concern over the safety of the existing nuclear systems. In view of all of this, there has been growing interest in solar energy systems as a means to supplement the world's energy needs.
Solar energy systems offer the advantages of being relatively safe and reliable and, obviously, are based upon a virtually inexhaustible source of energy.
Accordingly, it is a prime object of the present invention to provide a solar energy system which has high efficiency, ease of control, and reliable and continuous power output.
Exemplary of prior art solar energy systems over which the present invention has many advantages as will be seen hereinafter are the following described devices: In U.S. Pat. No. 3,983,704 which issued on Oct. 5, 1976 to Lorrell C. McFarland there is disclosed a solar energized thermodynamic motor in which solar rays heat a fluid to cause it to expand and be forced through a stand pipe to an elevated tank from which it can descend and drive a hydraulic motor. Another solar device is shown in U.S. Pat. No. 4,195,775 which issued April 1, 1980 to Edward T. Pitts in which the rays of the sun are concentrated by a mirror to heat water in a collector which moves with the mirror as the collector tracks the sun. A solar energy thermal collector which provides a high temperature thermal output in combination with a tracking system is disclosed in U.S. Pat. No. 4,210,463 which issued on July 1, 1980 to William J. D. Escher. A solar energy system which is utilized to convert water into steam for driving a turbine and generating electricity is shown in U.S. Pat. No. 4,280,328 which issued on July 28, 1981 to Claude J. Falconer. A method and apparatus for collecting, intensifying and storing solar energy which includes a hollow spherical vessel having a polished interior surface and which employs heat absorbing media such as metal shots which change from a solid state to a liquid state as solar energy is absorbed is disclosed in U.S. Pat. No 4,280,482 which issued on July 28, 1981 to Jack E. Nilsson, Sr., one of the inventors of the present invention. A method of continuously supplying a load by means of solar energy which utilizes heated molten metal and hydrogen storage is shown in U.S. Pat. No. 4,433,673 which issued to Donald E. Bierling on Feb. 28, 1984, and, an apparatus for collecting, intensifying and storing solar energy is shown in U.S. Pat. No. 4,449,515, which also issued to one of the inventors of the present invention.
Still another solar energy device has been proposed by United Sterling, Inc. Alexandria, Va. which employs a parabolic dish concentrator, a solar receiver, a Stirling heat engine, and a generator. The solar receiver takes the concentrated solar radiation from the parabolic dish and converts it into usable heat which is used to power a Stirling engine which, in turn, supplies the mechanical power needed to run an electric generator. The parabolic dish Stirling system is significantly more efficient than a photovoltaic system. Stirling engines of the type which can be employed in the present invention can be obtained from said United Stirling, Inc. and these engines have the flexibility of using either heat supplied by solar radiation or heat from gaseous or liquid fuel combustion. A Stirling engine works in a similar manner in terms of compression and expansion as does an internal combustion engine but it differs in that heat is supplied continuously and externally to the working gas which is usually hydrogen or helium and operates in a completely closed system. The thermal efficiency of such engines is relatively high.
Accordingly, one of the objects of the present invention is to provide a solar powered generating system which employs a highly efficient heat engine such as the Stirling engine.
Another object of the present invention is to provide a means for storing energy to assure continuous operation of a solar energy system.
Still another object of the present invention is to provide a means of controlling the power output of a solar powered Stirling engine by providing novel control means in connection with heat storage means.
Another object of the invention is to provide a system for generating electricity from solar energy and then converting the electrical power to hydrogen which is much easier to store for later use.
These objects are achieved and advantages are provided by the present invention which is described hereinafter.